Historically, gas-driven engines were the norm for compressors used in natural gas extraction. The engines were fuelled by natural gas from a pipeline, but the cost of gas has made it more profitable for the producer to sell the gas than use a portion of it for operations. Working with Schneider Electric a project was undertaken to convert the engines at two hundred of its well sites from gas-driven to electric motor.

The producer also wanted the ability to monitor more variables, including temperature and pressure, and to perform certain operations including idle, shut off, sleep mode, and restart if certain conditions were present. To achieve this, the compressor maker opted to install the ultra-compact Twido controller, which is especially designed for small control systems, and a Magelis XBT N text display human machine interface (HMI). Altivar 31 variable frequency drives (VFDs) were selected to match the compressors.

Improved control and  reporting

The control system offers gas producers access to more information about their system, such as pressures, temperatures, runtime, and immediate notification of a fault. The real-time data allows users to make more informed decisions and optimize operations.

Using a VFD to slowly ramp up the speed of the motor eliminates the inrush, which reduces wear on the motor and pump and improves equipment life. A VFD also allows users to control the speed of the pump and realise energy savings. For example, reducing the speed of the pump by as little as 10 percent can result in a 25 percent energy savings. In addition, a VFD gives gas producers more control over their pumping schedule as they can alternately run the pump at higher and lower speeds.

Remote monitoring

One of the biggest advantages to gas producers is remote monitoring capability. Generally, gas fields are located in areas that require technicians to travel long distances to reach the sites, making it difficult to effectively manage them. Remote monitoring limits downtime, since personnel can identify the problem ahead of time and then take any needed equipment with them, instead of having to make multiple trips for troubleshooting and repair. Technicians also can tune, update, and restart from a remote location.

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